April 9 (Bloomberg) -- The U.S. and Iran today escalated
their standoff over Iran’s choice for its next ambassador to the
United Nations, as diplomats in Vienna pushed forward at talks
on restraining the Islamic Republic’s nuclear program.

After President Barack Obama’s spokesman yesterday labeled
the selection of Hamid Aboutalebi, who has been linked to a
student group that took over the American embassy in Tehran in
1979, as “not viable,” a spokeswoman for Iran’s Foreign
Ministry today called the U.S. stance “not acceptable.”

Foreign Ministry spokeswoman Marzieh Afkham said in Tehran
that Aboutalebi is one of the Iran’s best diplomats. “The U.S.
administration’s approach to the Islamic Republic of Iran’s
representative to the UN is not acceptable,” he said.

Both governments said they have officially communicated
their positions. The White House press secretary stopped short
of saying that the U.S. would deny Aboutalebi a visa to serve at
UN headquarters in New York.

The U.S. and Iran have been inching toward repairing ties
broken after the takeover of the U.S. embassy in Tehran by a
group of radicals during the 1979 Islamic revolution that
resulted in 52 Americans being held for 444 days. One of the
major goals of U.S. policy has been getting an agreement that
would curb Iran’s nuclear development program.

U.S. Secretary of State John Kerry told a Senate panel
yesterday it would take Iran two months to produce enough
fissile material for one nuclear weapon.

Interim Agreement

Diplomats are meeting in Vienna today to set the terms for
meeting the deadline. Among the issues being discussed are how
sanctions on Iran would be lifted under a prospective accord.

The U.S. administration regards the dispute over the UN
envoy as separate from the nuclear issue, and Daryl Kimball,
executive director of the Arms Control Association in
Washington, said it’s unlikely to limit negotiations.

“I don’t expect the issue over the ambassador will
directly affect the talks in Vienna or the strong determination
of the P5+1 and Iran to reach a deal on Tehran’s nuclear
program,” he said in an e-mail.

Obama has authority to deny Aboutalebi entry to the U.S.

United Nations

Under the United Nations Headquarters Agreement Act
approved by Congress in 1947, the president can deny visas to
individuals deemed to pose a security threat to the U.S., said
John Bellinger, a former State Department legal adviser who is
now partner at Arnold and Porter LLP in Washington.

If Obama decides a person is a threat “then we’re not
required to give that person a visa, and that would be
consistent with our obligations under the headquarters
agreement,” Bellinger said. “Whether that’s good policy or not
that would be up to others to decide.”

The issue also is entangled in domestic U.S. politics.

Democrats joined with Republicans in the Senate on April 7
to pass legislation sponsored by Texas Senator Ted Cruz barring
Aboutalebi from entering the U.S.

“The United States Senate is not just going to ignore this
latest insult,” Cruz said of Iran’s envoy pick in a speech on
the Senate floor.

Domestic Politics

With Cruz a possible contender for the Republican
presidential nomination, the dispute is being pushed into the
2016 campaign with Obama in the middle.

“If he doesn’t accept the ambassador, then he runs into
problems with the Iranians,” said Anthony Cordesman of the
Center for Strategic and International Studies, a Washington
policy research organization. “If he does accept the
ambassador, he’s soft on Iran.”

Cordesman said he knew of no legal precedent for Congress
to block an ambassador or issuance of a visa, a responsibility
left to the executive branch.

Some of the same legal questions came up in 2005 when Iran
applied for a visa for then-President Mahmoud Ahmadinejad to
address the UN and they apply to Aboutalebi’s visa application.
Ahmadinejad was representative of a UN member state as would be
Aboutalebi, Bellinger said.

The Department of Homeland Security initially found
Ahmadinejad ineligible for a visa to enter the U.S. because of
suspicions he participated in the embassy seizure, only to have
the State Department grant it months later after interviewing
former hostages.

UN Committee

The UN’s Committee on Relations with the Host Country,
established in 1971, governs relationships between countries
where envoys are sent and the countries that send them. That
committee has 19 member countries including the U.S, Cuba, Iraq
and Libya. Iran is not a member.

The agreement prohibits the U.S. from imposing “any
impediments to transit” to or from the UN headquarters. The
State Department has suggested there are exceptions to the
agreement. UN delegates to the U.S. from Iran, North Korea, Cuba
and now Syria are allowed into a limited zone around the United
Nations building in New York and are restricted from other
travel in the U.S.

“We haven’t been dealing specifically with this case right
now” and it remains an issue between the U.S. and Iran, Farhan
Haq, UN deputy spokesman, told reporters yesterday in New York.
“If there’s a need for us to have a role down the line, we’ll
consider it.”